Easter bunny? Robbie the Rabbit is a recurring presence in the Silent Hill games, including in one of its most disturbing Easter eggs
Photograph: public domain

Legend has it that the 1979 Atari 2600 game, Adventure, was the first to include a hidden in-joke buried away in an obscure corner of the code. If players directed a grey dot into a hidden room they got to see the message “Created by Warren Robinett”, a self-referential protest by the game’s programmer who was annoyed at Atari for not crediting its staff.

Since then, it’s been discovered that the Fairchild Channel F console, launched in 1976, boasted several such messages. The demo cartridge that originally came with the machine had one, as did the 1978 title Video Whizball, a Pong derivative that would post the coder’s name on the screen (Bradley Reid-Selth) if you carried out a complex sequence of moves at the close of the game.

But whoever started it all, these hidden jokes, japes and sneaky references soon became a staple of video game design, earning the name Easter Eggs – probably in reference to traditional Easter egg hunts.

Anyway, here are 12 of our favourites. Add your own in the comments section.

Doom 2 – shoot John Romero in the face

“To win the game you must kill me, John Ro ... ow!”

The classic first-person shooter sequel featured a hidden ending that players could only discover by shooting the final boss monster in the face, then walking through it. On the other side of this grizzly scene, you discover the head of the game’s co-creator John Romero. On a stick. The game also plays a backwards sound file of Romero growling “To win the game you must kill me, John Romero!” So you do.

Batman Arkham Asylum – the hidden blueprint room

Warden Sharp’s plans for a city-sized asylum – either that or the world’s most grim theme park

This gothic masterpiece hides a sneaky hint about its own sequel. Players have to enter the office of the asylum warden, Quincy Sharp, and blow up a wall . What they’ll discover is a hidden chamber with a large blueprint on the wall showing a planned expansion of the asylum to take up a whole city sector – the setting, of course, for follow-up, Batman: Arkham City. The room was so well hidden it was undiscovered for two years until developer Rocksteady gave it away in a preview for the second title.

This “cute” fluffy toy makes several disturbing cameos throughout the Silent Hill series, but his creepy highlight is in The Room. Whenever lead protagonist Henry Townshend peeps through the hole in his bedroom wall to spy on his attractive neighbour Eileen Galvin (look, this is a Silent Hill game – this sort of thing just happens) he can see Robbie slumped on her bed. However, later in the game Galvin is rushed to hospital and, if the player peeks into her room again, Robbie is now turned toward the camera, terrifyingly pointing his foot at you – just like the scary monkey in Family Guy. Except pink. And a rabbit.

Dead Rising – Jill’s Sandwiches

Jill’s Sandwiches. “Do you serve flat breads?”

In Capcom’s original survival horror romp Resident Evil, lead character Jill Valentine is nearly squashed when she’s trapped in a room with an ominously lowering ceiling. Colleague Barry Burton rescues her just in time, though, exclaiming: “You were almost a Jill sandwich!” Later, the developer chose to celebrate its mastery of dialogue with this hilariously named burger joint.

The Hitman series is riddled with in-jokes and secrets, but this is one of the most visually rewarding. In the mission “Til death do us part”, the assassin lead character, Agent 47, must take out the groom at a redneck wedding. But when he goes over to a building behind the dancing guests and shoots a tiny coin submerged in a puddle a group of men in boxer shorts run over and start clapping him. Is this a clever reference to the great Simcopter controversy? Or just some men clapping in their boxer shorts? History will never let on.

A creeper making an unexpected guest appearance in the Gearbox shooter Borderlands 2 Photograph: public domain

In the game’s Caustic Caverns area, among the labyrinth of abandoned mining tunnels, players can find a hidden chamber filled with creepers, the exploding monsters from Minecraft. There are also several different Minecraft blocks that can be smashed to reveal loot and useful items (including blocky Minecraft heads for your character to wear). It’s only one of the several cultural references that Gearbox hid in its crazed sci-fi shooter – Dark Souls and Lord of the Rings also crop up.

In the mid-90s, Midway’s classic basketball sim thrilled arcade dwellers and console owners with its vast roster of real-life NBA players. But by entering secret codes, fans could also gain access to a range of 40 extra characters including the Beastie Boys, Bill Clinton, Sub-Zero from Mortal Kombat and, of course, DJ Jazzy Jeff and the Fresh Prince. Basically, if you were ever hoping to see politician and environmental campaigner Al Gore perform a slam dunk against Crunch, the team mascot of the Minnesota Timberwolves, this may be your best chance.

Portal – the lair of the Rat Man

At the start of Portal, malevolent computer program Glados promises you a treat for completing her tests. But Rattman seems to think you won’t get it

The Aperture science centre holds a wealth of disturbing secrets, but persistent players of Valve’s brilliant first-person puzzler could discover the best. Hidden away throughout Portal and its sequel are secret dens, the walls of which are covered in bizarre diagrams and notes. It’s all the work of scientist Doug Rattman who became trapped in underground lab and slowly went insane. One of Rattman’s scrawls is the now legendary phrase: “the cake is a lie”.

Ridiculous animal cameos are a regular Easter egg treat in games. Gears of War had its golden chicken, Diablo 2 had its secret cow level, and gangster epic Saints Row 2 has ...a giant purple bunny that emerges from the ocean. To witness this unusual natural phenomenon, players must make it to a tiny island hidden offshore amongst ever-rolling mists, and then just wander around near the coast until the cuddly Kraken wakes.

Metal Gear Solid 3 – the end of age

This is The End, my friend. At least it’s how he would have wanted to go: with a sniper rifle in his hands and a parrot on his back

Ever the prankster, Hideo Kojima has always crammed his Metal Gear titles with furtive jokes, tricks and secrets. In this one, if players save the game before a climatic boss battle with ageing sniper The End, and then set their PlayStation system clock forward several months, when they reload the game, The End has died of old age. Oh Kojima, you are a card.

Treyarch’s Cold War conspiracy shooter is full of secrets, naturally, but not all of them involve the Kennedys or Vietnam. On the creepy Nuke Town map, if you shoot the heads off all the dummies within 30 seconds, you get to sit down at an old Atari console and play a selection of retro Activision titles, including Pitfall and River Raid.

Grand Theft Auto V - the Thelma and Louise ending

“Let’s keep going – we’ll just respawn outside a hospital anyway!”

Everyone has their favourite Grand Theft Auto Easter egg – there are hundreds of them – but we love the poignant drama of this one. If you steal a chopper and fly over a certain mountainous location after 7pm in the evening, you see a vintage car reenacting the famous ending of Ridley Scott’s movie Thelma and Louise, driving over the edge of a vast edifice. There’s even a group of police cars nearby – although sadly you don’t get Trevor dressed as Harvey Keitel running toward the doomed duo.